I do not claim that my opinion is absolutely true.If you've spotted any mistake in my English, please, correct it. I want to be aware of any mistakes to efficiently eliminate them before they become a habit.

I do not claim that my opinion is absolutely true.If you've spotted any mistake in my English, please, correct it. I want to be aware of any mistakes to efficiently eliminate them before they become a habit.

Hmmm... can some носитель русского explain how the meaning would change if we replace the first стоит with есть (or simply drop it and use no verb), and the second стоит with надо or следует?

I'm especially interested in the second part of the question -- I mean, to my English-speaking mind, it would seem more natural to use стоит in cases where one has a CHOICE whether to pay money or not.

E.g., "когда не стоит покупать страховку?" ("When is it not worth[while] buying insurance?") -- but when I see the phrase "оплатить налог," I automatically think НАДО! It is not merely "advisable" or "a good idea," but "mandatory," right?

P.S. As an English note, "worth" and "worthwhile" can be considered synonyms when they are used as adjectives IN THE PREDICATE POSITION, as above.

I mean, to my English-speaking mind, it would seem more natural to use стоит in cases where one has a CHOICE whether to pay money or not.

You are right that "стоит" is more like "you should"/"it is good idea to...". But I see nothing unnatural in "you should pay taxes, otherwise there will be penalization" (at least in russian). It sounds absolutely ok. Every "should" has it's "otherwise".
So, replacements you are talking about, have no significant effect.
P.S.
Moreover, "should"-words (следует/хорошо бы) can be polite replacements for "must"-words (должны/обязаны).

I mean, to my English-speaking mind, it would seem more natural to use стоит in cases where one has a CHOICE whether to pay money or not.
E.g., "когда не стоит покупать страховку?" ("When is it not worth[while] buying insurance?") -- but when I see the phrase "оплатить налог," I automatically think НАДО! It is not merely "advisable" or "a good idea," but "mandatory," right?

Not too firm, but not too soft either. All in all it gives a good sense that there'll be repercussions if you don't do what's been recommended.

As for the original sentence:

Any Russian speaker will understand that this стоит doesn't really mean "should" but "must" in that sentence. It's just general politeness in there. A kind of euphemism if you will. Replace a strong word with a softer one, but still deliver the message of the strong word between the lines.

I do not claim that my opinion is absolutely true.If you've spotted any mistake in my English, please, correct it. I want to be aware of any mistakes to efficiently eliminate them before they become a habit.